Demographics: The number of children 14 or under is at its lowest since 1920. Some foresee a dearth of workers and taxpayers, reduced prosperity, even radical depopulation.

TOKYO — A challenging job, more than enough money and plenty of freedom. Hideko Arai figures she has it all--except what the Japanese government wants her to have: children.

With no plans for marriage and certainly no wish to rear a child on her own, Arai says her childless status is not going to change soon.

"If I decide I want to go somewhere, I can just go. If I want to go out on the town, I can go out," explained the 36-year-old marketing coordinator. "I have my own money and my own freedom."

Women like Arai are at the center of a national debate over what the government says is a top threat to the country's future: the declining birth rate.

The government fears that fewer babies--births are down to an all-time low of 1.39 per woman--will mean a less prosperous, more troubled and lonelier Japan. The trend will increasingly squeeze funds needed to provide for the rapidly increasing numbers of elderly among the 130 million Japanese.

The prospect of a childless future is forcing the country to confront an array of forces, from cramped housing to rigid traditional marriage roles, that discourage Japanese from having more children.

Japan is slowly changing to make it easier to rear children. Men are helping out more at home as women increasingly go to work. Baby-sitting agencies are sprouting up to fill the gaps in day care. More bosses are allowing employees to take time off to care for their children.

But the changes are not coming fast enough.

The Health and Welfare Ministry announced in June that the current birth rate is far below what's needed to keep the population steady. The number of children 14 or under--19.2 million--is at its lowest since 1920. Within a decade, the total population will begin to fall.

The trend will mean a shortage of workers to power the economy and a dearth of taxpayers to finance the staggering pension and health care bills of the future. The cost of those and other social services could quadruple by 2025.

"The balance between those who support and those who are supported has collapsed," said Hiroshi Choda, a policy analyst with the Health and Welfare Ministry.

In an apocalyptic projection illustrating the sense of crisis the government feels, a recent Health Ministry report estimated that if the current birth trend held up, the Japanese population could disappear sometime around 3500.

Schools are already closing in rural areas because there are fewer kids.

Despite the alarm bells, the government is unsure what to do. Officials are pushing day-care centers to expand hours and cut costs and have urged businesses to give employees more time to be at home, but there's little agreement on what else should be done.

Some of the causes of the declining birth rate are familiar in other countries, such as high rent and the rising costs of rearing children. Birth rates in Italy and Germany are even lower than in Japan.

But there are other factors that have particular resonance here.

One is the persistence of traditional marriage roles. Women by and large are expected to quit their jobs at marriage or when they have children and devote themselves to cooking, cleaning and rearing a family.

For Japan's growing ranks of well-educated career women, the life of a housewife seems unbearably humdrum. In a country where only 1% of children are born to single mothers, having a child outside marriage is not considered a serious option.

Arai, who works for the Max Wald computer consulting company in Tokyo, said she has the same attitude about marriage as many of her single contemporaries: She can take it or leave it.

"If I'm just going out with a man, our relationship can be equal," she said. "But once we get married, that balance would fall apart and he'll tell me to stay home."

More Japanese women are thinking like Arai.

The proportion of unmarried women in their 20s in Japan is nearing 50%. In 1972, nearly 80% of women thought it was better to get married; in 1990, that had plummeted to 40%.

Men are taking a dimmer view of marriage as well. Surveys find many bachelors in their 30s say they either haven't met the right person or prefer the freedom of being single. Both men and women are getting married at older ages.

The Japanese way of work has also come under scrutiny. The expectation that men will make their jobs their No. 1 priority is keeping fathers at the office late into the night and on weekends--meaning harried wives are left to run the household alone.

For working women, the demands of Japanese corporate culture often mean that mixing career and family is impossible. A glance around any Japanese office shows that women with career-track jobs are almost always single.

"I haven't had time to think seriously about my private life," said Sumiyo Shiosaka, 33, of NEC Home Electronics Ltd., who said she'd like to get married--but hasn't met the right man at the right time.